Alert archive / Connecticut / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 78, NWS Boston/Norton, MA

July 17, 2021Northeastern Connecticut Planning Region, Connecticut; Hampden County, Worcester County, Massachusetts

NWS Boston/Norton, MA issued this severe thunderstorm warning at Jul 17, 2021, 4:15 PM EDT for Northeastern Connecticut Planning Region, Connecticut; Hampden County, Worcester County, Massachusetts. It was in force for 60 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Jul 17, 2021, 4:15 PM EDT (20:15 UTC)
Expired: Jul 17, 2021, 5:15 PM EDT
In force: 60 min
Issued by: NWS Boston/Norton, MA
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Northeastern Connecticut Planning Region, CT, Hampden County, MA, Worcester County, MA

The radar

The Boston radar (KBOX), 86 km from the middle of the area, began a volume at 20:16 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Jul 17, 1:13 PM EDT	Severe Thunderstorm Watch	SPC	10 hr

The nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 8.3 hours before the alert went out and 142 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 1203 J/kg
Mixed-layer CIN: -55 J/kg
Mixed-layer LCL: 1054 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: 35 m²/s²
0-3 km storm-relative helicity: 46 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 1.0

Open this sounding in Storm Lab

The text

As transmitted.

598 
WUUS51 KBOX 172015
SVRBOX
CTC013-015-MAC013-027-172115-
/O.NEW.KBOX.SV.W.0078.210717T2015Z-210717T2115Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Boston/Norton MA
415 PM EDT Sat Jul 17 2021

The National Weather Service in Boston/Norton has issued a

* Severe Thunderstorm Warning for...
  North central Windham County in northern Connecticut...
  Northeastern Tolland County in northern Connecticut...
  South central Worcester County in central Massachusetts...
  Southeastern Hampden County in western Massachusetts...

* Until 515 PM EDT.

* At 415 PM EDT, a severe thunderstorm was located near Wales, or 15
  miles north of Mansfield, moving northeast at 10 mph.

  HAZARD...60 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Expect wind damage to trees and power lines. Minor hail 
           damage to vehicles is possible.

* Locations impacted include...
  Southbridge, Charlton, Stafford, Spencer, Dudley, Thompson,
  Sturbridge, Monson, Woodstock, Brimfield, Brookfield, Holland, East
  Brookfield, Wales and Union.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4195 7229 4204 7234 4222 7200 4199 7192
TIME...MOT...LOC 2015Z 242DEG 10KT 4201 7224 

HAIL...1.00IN
WIND...60MPH
 
$$

Chai

The office that day

Everything else NWS Boston/Norton, MA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 17, 1:59 PM EDT	Special Weather Statement	BOX		46 min
Jul 17, 3:26 PM EDT	Severe Thunderstorm Warning	BOX	Northeastern Connecticut Planning Region	64 min
Jul 17, 3:47 PM EDT	Areal Flood Warning	BOX	Northeastern Connecticut Planning Region	118 min
Jul 17, 4:14 PM EDT	Flash Flood Warning	BOX	Northeastern Connecticut Planning Region	5 hr
Jul 17, 4:18 PM EDT	Severe Thunderstorm Warning	BOX	Northeastern Connecticut Planning Region	57 min
Jul 17, 4:20 PM EDT	Special Weather Statement	BOX		40 min
Jul 17, 4:29 PM EDT	Severe Thunderstorm Warning	BOX	Northeastern Connecticut Planning Region	61 min
Jul 17, 4:38 PM EDT	Severe Thunderstorm Warning	BOX	Capitol Planning Region	67 min
Jul 17, 4:58 PM EDT	Flash Flood Warning	BOX	Capitol Planning Region	2 hr
Jul 17, 5:21 PM EDT	Flash Flood Warning	BOX	Capitol Planning Region, Northeastern Connecticut Planning Region	5 hr
Jul 17, 5:30 PM EDT	Flash Flood Warning	BOX	Northeastern Connecticut Planning Region	3 hr
Jul 17, 2:37 PM EDT	Special Weather Statement	BOX	Franklin	38 min
Jul 17, 2:45 PM EDT	Special Weather Statement	BOX	Plymouth	45 min
Jul 17, 2:53 PM EDT	Special Weather Statement	BOX	Hampshire	52 min
Jul 17, 2:53 PM EDT	Severe Thunderstorm Warning	BOX	Bristol, Norfolk	52 min
Jul 17, 3:36 PM EDT	Areal Flood Warning	BOX	Bristol	114 min
Jul 17, 4:05 PM EDT	Severe Thunderstorm Warning	BOX	Worcester	34 min
Jul 17, 4:34 PM EDT	Severe Thunderstorm Warning	BOX	Middlesex, Worcester	36 min
Jul 17, 4:48 PM EDT	Flash Flood Warning	BOX	Worcester	3 hr
Jul 17, 5:10 PM EDT	Severe Thunderstorm Warning	BOX	Middlesex, Worcester	65 min
Jul 17, 5:34 PM EDT	Special Weather Statement	BOX	Hampshire	41 min
Jul 17, 5:35 PM EDT	Flash Flood Warning	BOX	Hampden, Hampshire	3 hr
Jul 17, 6:04 PM EDT	Flash Flood Warning	BOX	Hampden, Hampshire	3 hr
Jul 17, 6:05 PM EDT	Severe Thunderstorm Warning	BOX	Bristol	26 min
Jul 17, 7:49 PM EDT	Areal Flood Warning	BOX	Hampden, Worcester	116 min

Nearby

Severe Thunderstorm Warnings in Connecticut, 2021 Severe Thunderstorm Warnings in Massachusetts, 2021 Every severe thunderstorm warning in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.